Automatic pulsator for milking machines



March 16, 1943. c. H. HAPGOOD AUTOMATIC PULSATOR FOR MILKING MACHINES Filed 0c c. 17, 1940 3 Sheets-Sheet 1 March 16,1943. c. H. HAPGOOD 2,313,822

AUTOMATIC PULSATOR FOR MILKING mAcnmss Filed Oct. 17, 1940' a Sheets-Sheet 2 Haj.

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AUTOMATIC PULSATOR FOR-MILKING MACHINES Filed Oct. 17,:1940 3 Sfieets-Sheet :5

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I wmvrm Mme-s8.- I A 1 /225 owargf/a v yaaq tiori for eifecting said Patented Mar. 16, 1943 UNITED STATES PATENTVOFFICE AUTOMATICPULSATOR FOlt MILKING MACHINES Cyrus Howard Hapgood, Nutley, N. 3., assignor to The" De Laval Separator Company, New York, N. Y., a corporation of New Jersey Application October 17, 1940, Serial No. 361,540 6 Claims. (01. 3161) In an application filed by me October 17, 1940,

pressure areas, means operablein each stroke of i the pulsator to make connections with sources of high and low pressures adapted to establish comparatively high diiferential pneumatic pres? sures on said opposing areas to thereby prevent the reversal of the pulsator, and means for flow of air between said areas until the differential:

pneumatic pressures are gradually reduced, momentarily balanced and then reversed; thereby eifecting the reversal of the ,pulsat'or under comparatively low differential pressures until, in the reverse movement" of the pulsator, the high novelty. No claimyis herein made to the said construction, described and illustrated in my said application filed of even date herewith, having novel structural features in common with the construction, herein described, and illustrated,

embodying said other features of specific novelty;

the claims herein being directed solely to the latter construction.

Fig. 1 is a vertical sectional View of such a pulsator.

j Fig. 2 is a cross-section on the line 2-4 of Fig. 1.

Fig. 3 is a vertical sectional view of the pulsator mounted on a milk pail, the valve beingshown in its down position.

Fig. 4 is an end view of one of the piston heads,

* Fig. 5 is a diagram illustrating the air pressure conditions at thestages of operation of the pulsator shown in the table included in the description V l I In-the cylindrical body or piston chamber a reciprocates the pistonval ve b; Piston chamber differential pressures are again established'as above 'specified i l V The specific pulsator disclosed "said applica operationcomprises a. piston. chamber opening into a casing which is divided by a diaphragm (of-l'argearea relative to the piston heads) into two chambers between which air is adapted to constantly fiow, the

chamber nearer the pistonichamber constantly communicating therewitlfland means, including 3 i ports and passages, operable in one stroke of the piston to connect the near diaphragm chamber with the atmosphere and the far end of the piston chamber with (partial) vacuum. and in the other stroke of the piston to. connect the near diaphragm chamberwith (partial) vacuum and the far end of the chamber with atmosphere. While such specific pulsatorso constructed is a preferred embodiment of. the broad invention,

the operation above described is not a mere function of such pulsator, since it embodies specific features which are not essential to the described operation In the drawings forming part of this application and in the following description, I disclose another construction having the operation above described and having novel structural features in common therewith, but

which also embodies other features of specific a opens at opposite ends into casings cand d. The pulsator occupies (preferably) a vertical position. Inthisposition thelower-casing c is divided by a diaphragm e-into chamber 7 and an outer or The upper casing dis divided by a diaphragm h into aninnerfor lower chamber i and an outer or upper chamber 7'. The chambers on opposite lower chamber 9.

sides of each diaphragm are "in constant pneu-v 1 maticcommunication i by means of an'air pasa sage lei The rateot flow of the air through such passage is controlled by a valve m. Each diaphragmmay ,be adisc of rubber, rubberized fabric or otherflexible material,having on opposite sides rigid (metal) reinforcing plates :10.

The piston valve b comprises end heads and a central portion b, all of a" diameter corresponding to that of the piston chamber a so as to have a sliding fit therein, the central portion and the end heads being connected by necks of reduced diameter.

The piston chamber is provided with air ports 0 and p; a central port communicating with a nozzle 2' which isconnectedwith a source of vacuum (which, as is customary, 'is prefer-u ably an absolute pressure of about half an atmosphere); and ports connected with nozzles s and t, which are adapted to connect respectively with the inflation chambers of two difierent pairs of a set of fourteat cups (not shown). A passage it extends from the space surrounding the lower neckof the piston through the center of thelower end, head of the piston and there connects with and passage 11 and also a V-shaped groove 2 extending across the end face of said head, thereby ailording pneumatic connection between said space and the diaphragm chamber 1. A passage 11 extends from the space surrounding the upper neck of the piston through the center of the upper end head of the piston and there connects with a V-shaped groove y extending across the end face of said head, thus aifording pneumatic connection between said space and the diaphragm chamber 2'.

Studs w, projecting inward from the end walls of the casings c and ct in line with the piston, limit the outward flexing of the diaphragms.

In Fig. 3 the pulsato-r is shown mounted on top of a milk pail Hi. It may be supported on mosphere But immediately upon establishing the pneua standard H secured to an annular member 12 extending from the top of the pail and enclosing a chamber l3 communicating with a nozzle M adapted for connection with a source of vacuum. The supporting standard i l is shown as provided with a channelconstituting a prolongation of the nozzle 1" of'Fig. land communicating with the vacuum chamber l3. I5 is a .double valve of known type, such, for example,- as shown in the Leitch Patent No. 1,394,433, dated October '18, 1921, which, when vacuum is established in the chamber i2, is opened to thereby connect the milk pail with vacuum. The top of the milk pail is provided, as usual, with a nozzle Iii adapted for connection with the milk chambers of a set of teat cups, to thereby maintain a constant vacuum therein during the milking operation. In order to show both the web and the valve m in a single figure, the valve is shown in the plane of the web. In the actual construction, the valve should be positioned outside such plane that is,

to one sidecf nozzle 1', as shown in Fig.

When the pulsator isnot in use all chambers and all portsand passages are filled with atmospheric air. When, priorto connecting the nozzle 1*. with vacuum, the pulsator is positioned for use (usually on top of a milk pail'as shown in.Fig. 3) the piston valve drops by its own weight. When, therefore, nozzle r'is connected' with vacuum, air is exhausted from chamber ithrough grooves 1 from the inflationcham-- bers of the pair-of teat cups connected with nozzle it. There is thusrestablished anunbalanced pressure on the opposite ends of the piston valve,

the lower end being subjectedto atmospheric- This unpressure and the upper end to vacuum. balanced pressure tends to shift the-valve into its upper position. Since, howeventhe areas of the. diaphragms are multiple times the areas or" the piston ends, and since chamber j is under atmospheric pressure and chamber 1' undervacuum, the thrust tending to hold the valve'down (diaphragm It being flexed down by the higher pressure above it) greatly tending to lift the valve. But immediately upon establishing the pneumatic connections described, air starts to flow from chambera' to chamber It is not, however, until these pressures are so nearly balanced that the difference in thrusts on opposite sides of diaphragm h is reduced to just below the difference in thrusts on opposite ends of the piston that the higher thrust on the lower end of the piston becomes effective to raise it, thereby flexing diaphragm h upward and reversing the pneumatic connections; that is, air is then exhausted from chamber 1 through grooves z and port a and also from the inflation chamflow from chamber g to as aseo mosphere through grooves y and passage 11. There is now established a reverse unbalanced pressure on the opposite ends of the piston valve; that is, the upper end is subjected to atmospheric pressure and the lower end to vacuum, which unbalanced pressure tends to return the valve to its lower position. But since chamber g is now under atmospheric pressure and chamber 1 under vacuum, diaphragm e is flexed upward and prevents the weaker downward thrust on the valve from being effective to move it down. At the same time diaphragm h is flexed upward by reason of the connection of chamber 2' with atwhile chamber 7' is under low pressure.

matic connections just described, air starts to chamber 3 and from chamber 2' to chamber 9'. When these pressures become so nearly balanced that the differences in the thrusts are reduced to just below the difference in thrusts on opposite ends of the piston, the thrust on the upper end of thep'iston becomes effective to lower it; thereby (while flexing diaphragm e downward) again reversing the pneumatic connections; that is, air is exhausted from chamber '2' and from the pair of teat cups connected with nozzle t; and chamber f and the pair of teat cups connected with nozzle s are again connected with the atmosphera. The pressures on opposite ends of the piston are thus again reversed, but the higher pressurein chamher is effective to hold the piston down (the diaphragm e being also flexed down by the higher pressure above it), until, by reason of the flow of air from above, to below the diaphragms the diaphragm thrusts become so .nearly balanced that the valve again moves up by reason of the higher thr'uston its lower end. 1 The length (measured vertically)foi the cen tral part b ofpiston I) should be somewhat greater. than the length of the port opening into nozzle r, thusa-ffording sufiicient lap to prevent substantial leakage of air around the part b dur-- ing its tion lying'above nozzle 1' and the lower face of therpartition lying above port 0. Similarly, the

distancebetween the loweredge of thecentral part b of the piston andthe lower edge of the enlarged upper ,portionof the piston is shown as equal torthe distance between the upper face ."of the partition' lying "below nozzle 1 and the upper-face of the partition lying below port 10.

ihese dimensions .insure that chamberi, and port i will connect with vacuum simultaneously with exceeds the thrust bers oi the pair of teat cups connected with nozthe connection'of' port 8 and chamber '3 with pressure, and vice versa.

In the described construction there is no me-t chanical'conne'ct'ion between the piston valve and the diaphragms. The piston valve thus acts-as its'own motor. Each diaphragm merely'acts to hold the piston, after it is moved to one "end position from immediately returning to the other end position. The rate of flow of air between opposite sides of each diaphragm is so controlled as to accurately fix the rate of pulsation. i

The following diagram graphically illustrates one complete series of operations, A and Vindicating whether the pressure in the several diaphragmchambers is atmospheric or a 'partial vacuum at each of the stages, the arrows indicating the direction of the and diaphragms:

thrusts of the piston Operating Stages 1 The pressures in the spaces between the central member and the end heads of the piston may be ignored, since in all positions of the piston the pressure on the annular inner face of either end head and the pressure on the opposing annular face of the central member exactly balance.

Let it be assumed that the piston is in the down postion shown in Fig. 3, air filling the entire pulsator, and that nozzle r is connected with vacuum. The immediate effect is to connect diaphragm chamber 2 with vacuum. See vertical columnl. The thrust on the piston is then up, but the thrust on diaphragm h, which is many times the area of the piston head, is down and there is no movement of the piston. However,

leakage of air from diaphragm chamber 7 to.dia-,

phragm chamber 1' proceeds until the pressure in chamber 7' is reduced to so nearly that of the pressure in chamber 2' that the continuing upward thrust on the piston exceeds the downward thrust on diaphragm h, whereupon the upward thrust on the piston becomes effective-to move it towards its up position. See column 2. In this column V+ indicates that the pressure in chamber y is slightly above that in chamber 2' when the piston begins its upward movement. Momentarily in the upward shift, the spaces between the end heads of the piston and the cen tral part b are cut 01? from both vacuum and pressure (see Fig. 1); but since the pressures in each of these spaces upon the end head and the central part are balanced, as above stated, and as'the pressures on the two sides of each diaphragm approach closer to equality, their re-' sistance to movement of the piston reduces and allows the piston to continue its up stroke until, after passing its central position, chamber 2' connects with atmosphere and chamber f with vacuum, as shown in column 3, thereby creating an upward pressure on both diaphragms. The diaphragm h then immediately completes its upward movement, and while a downward thrust on the piston becomes operative, the upward thrust on diaphragm c, owing to its large area, so greatlyexceeds the downward thrust on the piston that a powerful impetus is given to the completion of the up stroke of the piston, which is then held in its up position by high differential pressures.

As soon as chamber 1 is connected with the atmosphere, as above described, the piston, as above stated, is subjected to a downward thrust, and air begins to flow from chamber 2' to chamber y and from chamber 9 to chamber ,1 until the pressures on opposite sides of each diaphragm are nearly balanced, as shown in column i. A- indicates that the pressure in'chamber :i is slightly below atmospheric and V+ indicates that the pressure in chamber g is slightly above. that in chamber 1. Thereupon the above specified downward thrust on the piston becomes effective to start it down. As the pressures on the two sides of each diaphragm approach closer to equality,

their resistance to movement of the piston reduces and allows the piston to continue its stroke until, after passing the center, chamber 2' is connected with vacuum and chamber 1 with the atmosphere, as shown in column 5, thereby creating a downward thrust on both diaphragms. The diaphragms then immediately complete their downward movement, and while an upward thrust on the piston becomes operative, the downward thrust on diaphragm h, owing to its large area, so far exceeds the upward thrust on the piston that a powerful impetus is given to the completion of the down stroke of the piston, which is then held in its down position by such differential pressure.

As soon as the chamber f is connected with the atmosphere, asabove described, the piston, as above stated, is subjected to an upward thrust and air begins to flow from chamber j to chamberg and from chamber 7' to chamber 2 until the pressures on opposite sides of each diaphragm are nearly balanced, as shown in column 6. Thereupon the above specified upward thrust on the piston becomes effective to move it up. Just before it completes its stroke, chamber is connected with vacuum and chamber :1 with the atmosphere, as shown in column 3.

Column 6 shows substantially the same pneumaticconditions as column 2. During the operation of the pulsator, columns 3, 4, 5 and 6 illustrate the complete cycle of movements. Column 1 merely illustrates the pneumatic conditions when the operation of the pulsator is started by connecting the pulsator with vacuum, while column 2, as hereinbefore described, indicates the pneumatic conditions in the immediately following stage.

It will be understood that the pneumatic conditions illustrated in the columns of the table do not represent static conditions. The piston remains stationary, alternately at one end and at the other end of its stroke, for the major part of the time of operation. The line designated movement of piston under columns 2, 4 and 6 actually indicates the start of movement of the piston, which is indicated as completed incolumns 3 and -5, the piston being stationarybetween columns 3 and 4 and between columns 5 and 6. Each of the chambers z and f is always (except for a moment in the middle of the stroke of the piston) in communication with either atmosphere or (the established partial) vacuum. The pressure in each of the chambers y and g is constantly changing from nearly atmosphere to nearly vacuum or from nearly vacuum to nearly atmosphere. The precise pneumatic conditions in columns 1, 2, 3, 4, 5 and 6 are more accurately illustrated in Fig. 5, in which A indicates atmospheric pressure and V the established partial vacuum, the figures 1, 2, 3, 4, 5 and 6 corresponding to the figures l, 2, 3, 4, 5 and 6 of the table. From this figure 5 it will be understood that the time intervals between positions 3 and 4 and between positions 5 and 6 are relatively long and that the time intervals between positions 4 and 5 and positions 2 and 3 (or 6 and 3) are relatively short; that is, the movements of the piston, which occur between 4 and 5 and between 6 and 3 (or 2 and 3) are very rapid and accelerated; it completes its stroke in either direction in a period very short compared to the periods during which it remains at one or the other end of its stroke, which are the periods between 8 and 4 and between 5 and 6. From Fig. 5 the air pressure conditions in all the four chambers at 4 any given movement in the cycle can be seen at a glance.

While, as above stated, there is no mechanical connection between the piston valve and the diaphragms, the pulsator would be operative if the piston ends were connected to the diaphragm. Thus, in the down position of the piston, the upper sides of both diaphragms would be under high pressure and the lower sides under low pressure and both diaphragms would be flexed down and the piston held down. Owing, however, to the new of air through the conduits k the pressures on both diaphragms would soon become nearly balanced, but since the effective area on the lower side of the lower diaphragm would exceed the pressure on its upper side (due to the area of the lower side exceeding the area of the upper side by the cross-sectional area of the piston) the piston would be raised. It is true that, at the same time, the effective area of the upper side of the upper diaphragm would exceed that of its lower side, but since the absolute pressures on the lower and upper diaphragms would be respectively high and low, the pressure tending to move the piston up would exceed the pressure tending to move the piston down. The two constructions are, therefore, equivalents.

In the foregoing description I have assumed that the upper and lower halves of the pulsator are of precisely the same construction. If, however, the pulsator is in operation positioned vertically, there is always a minor force tending to move the piston down, namely, the weight of the piston. To compensate for, or equalize, this force, so that the rates of the upward and downward motions of the piston may be equal, the dimensions of certain corresponding parts may be made unequal. For example, the lower head of the piston may be of a diameter slightly greater than the upper head; or the valves m may be adjusted to provide a slightly more rapid flow through the air passage is in the lower casing than through the air passage is in the upper casing; or the rigid reinforcing plates :1: of the diaphragm may be varied in size, as, for example, the reinforcing plates on diaphragm 6 may be made slightly larger than those on diaphragm h, or the plate on the lower side of one diaphragm, or the plates on the lower sides of both diaphragms, may be made slightly smaller than on the upper side.

It will be understood that the high and low pressures operative to effect and control the pulsations need not be respectively atmospheric and partial vacuum, since any substantially different absolute pressures would effect the same operation.

What I claim and desire to protect by Letters Patent is:

1. An automatic pulsator for milking machines comprising end casings and a connecting piston chamber, a valve piston reciprocable in the piston chamber, diaphragms of large diameter relative to the piston, one in each casing dividing each casing into an inner chamber and an outer chamber, and means, including ports and passages, operative, in one stroke of the piston, to connect one inner diaphragm chamber with high pneumatic pressure and the other inner diaphragm chamber with low pneumatic pressure and in the other stroke of the piston to reverse said connections, and continuously open air flow conduits one connecting opposite sides of each diaphragm.

2- An automatic pulsator for milking machines comprising a piston chamber and a piston reciprocable therein, diaphragms, of large diameter relative to the piston, one side of each diaphragm and the corresponding end of the piston being always subjected to the same pneumatic pressure, means, including ports and passages, adapted, in each stroke of the piston, to connect one end of the piston with a source of high pressure and the other end of the piston with a source of low pressure and in the opposite stroke of the piston to reverse said connections, and air conduits one connecting opposite sides of each diaphragm, said air conduits allowing flow of air after the piston has completed its stroke until the pneumatic pressures on opposite sides of both diaphragms are nearly balanced, thereby allowing the higher pressure on one end of the piston to become efiective to reverse the piston.

3. An automatic pulsator for milking machines comprising a cylindrical valve chamber, a valve piston reciprocable therein, means, including ports and passages, operative when the piston is at either end of its stroke to connect one end of the valve with a maximum high pressure and the other end of the valve with a minimum low pressure, diaphragms at opposite ends of the piston .having areas multiple times thatof the piston and each having one side always exposed to the same pressure as the adjacent end of the piston, and a constantly open passage between opposite sides of each diaphragm.

4. In an automatic pulsator for milking machines, a cylindrical valve chamber, a valve piston reciprocable therein, sources'of high and low pressure, ports and passages so located that when the piston reaches either end of its stroke the advanced end will be connected with the source of high pressure and the trailing end with the source of low pressure, such differential pressures thereby tending to immediately reverse the piston, casings at opposite ends of the valve chamber, diaphragms, having areas greatly exceeding the area of the piston, one in each casing dividing the same into an outer chamber and an inner chamber, the latter being always exposed to the same pressure as the corresponding end of the piston, and a passage for flow of air between the two chambers of each casing, whereby, after each stroke of the piston, the diaphragm adjacent the trailing end of the piston will be flexed toward said piston end and hold the piston from reversal until, after the pressures on opposite sides of the diaphragms are nearly balanced by said air flow, the pressure on the advanced end of the piston will become efiect-ive to reverse it.

5. An automatic pulsator for milking machines comprising end casings and a connecting piston chamber, a valve piston reciprocable in the piston chamber, diaphragms of large diameter rela tive to the piston, one in each casing dividing each casing into an inner chamber and an outer chamber, and means, including ports and passages, operative, in one stroke of the piston, to connect one inner diaphragm chamber with high pneumatic pressure and the other inner diaphragm chamber with low pneumatic pressure and in the other stroke of they piston to reverse said connections, and continuously open air flow conduits one connecting opposite sides of each diaphragm, said outer chambers being closed against admission or exhaust of air except through said conduits.

6. An automatic pulsator for milking machines having opposing pneumatic pressure surfaces,

sources of high and low pressure, means, including ports and passages, adapted in the movement of the valve in each direction to connect certain of said opposing pressure surfaces with said sources of high and low pressure respectively, and thereby establish high differential pneumatic pressure on opposing pressure surfaces adapted to hold the valve at each end of its stroke, and air flow means having no direct connection with said sources of high and low pressure through 10 which, while the valve is at either end of its stroke, opposing pressures are gradually reduced, momentarily balanced and then reversed to establish low diiferential pneumatic pressures on opposing pressure surfaces to thereby move the valve in the opposite direction, said pulsator comprising a piston valve and diaphragms at opposite ends of the valve, which are subjected to the differential pressures specified.

CYRUS HOWARD HAPGOOD. 

